Sample valve



Jan. 26, 1965 R. c. KOELLER ETAL 3,

SAMPLE VALVE Filed Sept. 25, 1961 2 Sheets-Sheet l W. C. ZIEGENHAIN R. C. KOELLER INVENTORS ATTORNEY Jan. 26, 1965 R. c. KOELLER ETAL 3,156,939

SAMPLE VALVE Filed Sept. 25, 1961 2 Sheets-Sheet 2 W. C. ZIEGENHAIN R. C. KOELLER INVENTORS BY Wm ATTORNEY United States Patent Filed Sept. 25, 1961, Ser. No. 149,576 1 Claim. (Cl. 73-422.)

Our invention relates to sample valves of the type used to collect a sample of a fluid for transfer to an analytical instrument. More specifically it concerns a device for collecting a small sample of fluid under high pressure and purging the sample from the device at an elevated temperature.

For example, in the analysis of mixtures of volatile components by gas chromatography, a standard volume of the mixture is injected into the chromatographic column. A gas, typically helium, is passed through the column at a constant rate to fractionate the components of the mixture. Mixtures which are either a gas or a liquid at room temperature and atmospheric pressure can be introduced into the column with available sampling equipment. Fluids having a high vapor pressure at room temperature and which produce a two phase mixture when the pressure is reduced to atmospheric cannot be handled conveniently with available equipment. Samples of fluids produced from oil reservoirs sometimes have a vapor pressure of 5000 p.s.i. or higher. To obtain an accurate chromatograph of such fluids, a composite sample must be transferred to the column. Owing to the high pressure of the fluid, it is desirable to use a small volume sample, usually less than 0.1 cc., in order that the length of time to complete the analysis will not be needlessly extended. Additionally, it is sometimes desirable to heat the sample container to a temperature as high as 300-400 F. to increase the vapor pressure of the heavier components of the sample.

It is therefore an object of our invention to provide a sample valve for collecting a small volume of a fluid having a high vapor pressure whereby the sample can be transferred to an analytical instrument. It is also an object of our invention to provide apparatus which can be used to collect and transfer a sample without introducing contaminants. An additional object is to provide apparatus whereby the flow rate of purge gas can be established, then the sample introduced to the chromatographic column without interrupting the flow of gas. Another object is to provide a high-pressure sample valve which can be heated to assist the removal of the sample by a purge gas.

Briefly described, the apparatus of our invention comprises a unique arrangement of four needle valves in close proximity with their seats joining a sample chamber common to all of the valves. Flo-w lines connected to the valves provide for flushing of the sample chamber through one pair of valves with the fluid to be sampled, then collection of an uncontaminated sample. Thereafter air or other contaminating gases can be purged from the other pair of valves and connecting lines before the sample is transferred to the analytical instrument.

Our invention will be described by referring to the following dr-awings which illustrate a sample valve of the type disclosed herein.

FIGURE 1 is an isometric view of the apparatus showing the arrangement of valves and tubing connections.

FIGURE 2 is an isometric presentation of the flow passageways in the structure shown in FIGURE 1.

FIGURE 3 is a vertical section along line 33 of FIGURE 1 showing the positions of the several valves in relation to the sample chamber.

Bdhhfi Patented Jan. 26, 1965 ice Referring to FIGURE 1, composite valve body 10 contains four separate valve assemblies, 11, 12, 13 and 14. Tubes 15 and 16 provide fluid inlet to the structure while tubes 17 and 18 provide fluid outlet. From FIGURE 3 it can be seen that valves 11, 12, 13 and 14 are needle valves of the type commonly used in controlling the flow of high-pressure fluids in small-diameter lines. Valve 11, for example, has packing gland 35 sealing valve member 31 in body 10. The valve handle is turned to move valve member 31 into a sealing engagement with valve seat 21.

FIGURE 2 illustrates the pattern of flow conduits through the valve body. Valve chamber 4-1 contains valve seat 21 at the inlet to sample chamber 27, port 2%) on by-pass 19, and port 2% on sample inlet line 15. Thus, valve chamber 41 serves as a manifold for by-pass 19, line 15 and sample chamber 27. Referring again to FIGURE 3, it will be seen that valve member 31 closes valve seat 21 without interrupting the flow between line 15 and by-pass 11 through chamber 41. Similarly, valve chamber 43 at the opposite end of sample chamber 27 serves as a manifold for valve seat 23 adjacent the sample chamber, port 28 at the outlet of by-pass 19, and port 313 on fluid outlet line 17. Valve chamber 42 includes valve seat 22 which is in communication with sample chamber 27. Sample inlet line 16 joins valve chamber 42 at inlet port 25'. Valve chamber 44. is in fluid communication with the sample chamber by Way of valve seat 24. Sample outlet line 18 joins valve chamber 44 at port 26. This sample valve assembly is preferably made of a corrosive-resistant metal such as stainless steel. The packing glands on the needle valves may comprise Teflon gaskets and a brass follower.

To collect a sample in this valve, the four needle valves should be closed against their respective valve seats. Line 16 is then connected with the sample bomb containing the material to be sampled. When this connection has been completed, the valve on the sample bomb and sample inlet valve 12 are opened, enabling the material to flow toward the sample chamber. Sample outlet valve 14 is carefully opened to purge fluids from the system which are foreign to the material being sampled. When the lines are purged, sample outlet valve 14 is closed tightly then sample inlet valve 12 is closed. Chamber 27 now contains a sample of the fluid confined by closed valves 11, 12, 13 and 14. The sample valve may be disconnected from the system and delivered to a laboratory for analysis of the collected sample.

The sample is unloaded for analysis by gas chromatography by connecting line 15 to a source of purge gas such as helium. Outlet line 17 is connected to the sample entry line on the chromatographic column. The desired helium flow rate through the sample valve and column is established. In FIGURE 2 it can be seen that helium entering line 15 passes through valve chamber 41 and enters by-pass 19. From there it passes through valve chamber 43 and enters line 17. Thus the flow of purge gas can be adjusted to the desired rate, e.g., 30-50 cc./min., before the sample is introduced into the column. This flow should be continued for several minutes to sweep air from the apparatus. Thereafter the sample is transferred to the column by opening valves 11 and 13 simultaneously. This will permit the helium to sweep the sample between valve chambers 41 and 43. Transferring the sample from the closed chamber directly into the helium stream avoids contamination of the sample with air or other foreign materials which might be introduced if it were necessary to connect the sample valve into the system after the system has been purged. Heat may be applied to the sample valve as an aid in discharging low-vapor-pressure components. An electrical heating tape or mantle as Well as a steam bath or open flame might be used to supply the 7 i heat; Purge gas should be flowed through the sampler during the entire chromatograph run.

It can be seen that this apparatus permits the establishment of the desired purge rate before sample introduction and the continuance of the purge Without interruption while the sample is introduced. A constant how of purge gas is necessary for greatest accuracy in the analysis.

The volume of sample chamber 27 is designed to collect a sample which will permit an accurate analysis without excessive running time. Where the sample is collected at high pressure, e.g., 5000 psi, the chamber volume may be as small as 0.03 cc. Larger sample chambers may be used Where sampling pressure is lower or Where a larger sample is necessary to obtain the desired analytical accuracy. The volume of the chamber can be varied by changing either the length or the diameter of the chamber. A minimum length is necessary to'accommodate the four valve chambers in the sampler.

From the above it can be seen that this sample valve enables the taking of small samples at high pressure. Also the samples can be transferred to the gas chromatograph Without interrupting the pre-set flow of purge gas to the column and Without the possibility of sample contamination during the transfer.

While We have described our invention in relation to the embodiment illustrated in FIGURES 1 to 3, it should be realized that other configurations are possible without departing from the spirit and scope of our invention.

We claim:

A high-pressure fluid sampling valve comprising a com posite valve body, four needle valves extending into said body with their stems lying in a plane and oriented 90 apart, the chambers and seats of two opposite ones of said four valves being at the two respective ends of a central passage through said body forming a sampleholding chamber therein, and the chamber and seat of each of the other two opposite ones of said four valves being at the end of a short passage extending perpendicularly from said central passage near a corresponding one of its ends, four passages each extending from a chamber of a corresponding one of said four valves outwardly through said body perpendicular to said plane, two of said four passages extending in the opposite direction from the remaining two of said passages, each two of said passages having the same direction extending from the chambers of two adjacent valves having their seats farthest apart within said body, and a high-pressure by-pass passage including a tubing external to said body connecting the chambers of two opposite ones of said valves.

References Cited in the file of this patent UNITED STATES PATENTS Campbell Aug. 8, 1944 OTHER REFERENCES 

